Key ring guards are known. For example, U.S. Pat. No. 1,626,987, May 3, 1927 to J. P. Venegas for "Key Lock" describes a key ring in a guard or lock which is released or locked by a handle advanced or retracted. When retracted the ring may be turned or rotated to an open segment on which keys may be threaded or unthreaded. When the segment is returned to a lock position, the guard is advanced to a lock position preventing rotation of the ring. In U.S. Pat. No. 2,615,324 to Meeker, Oct. 28, 1952 for "Key Ring", the patentee suggests a key ring having a guard mechanism which is rotated to uncover an open segment of a ring on which keys may be returned to cover the open segment and prevent the threading or unthreading of keys on the segment.
U.S. Pat. No. 2,855,775 to Marien, Oct. 14, 1958 for "Key Holder" suggests a key ring having an open segment, and a spring actuated interposer which enters the open segment when the latter is in opposed position to the interposer. When retracted, the interposer admits a rotation of the ring to expose the open segment for threading or unthreading keys on the ring; when interposed the segment is not exposed and threading or unthreading keys is not possible. U.S. Pat. No. 3,362,201 to Lachin, Jan. 9, 1968 for "Key Holder" shows a spring loaded interposer which enters into a ring segment to prevent threading or unthreading keys on the ring; when the interposer is withdrawn, the ring may be rotated and keys threaded or unthreaded upon it. U.S. Pat. No. 3,635,058 to Polk, Jan. 18, 1972 for "Keyring Construction" proposes a spring loaded assembly of two parts, one of which is a segmented key ring. The spring prevents separation of the parts and holds the segmented part of the segmented ring in a position to be closed by the other part, also in the form of a ring. On separation of the parts against the spring loading, the segmented ring may be rotated for engagement or disengagement of keys; when returned to position in which the segment is closed, the keys are guarded in place. U.S. Pat. No. 4,079,607 to Spruyt, Mar. 21, 1978 for "Key Ring Structure" describes a key ring having an open section or segment, and a spring loaded cover urged into covered position to cover the open segment and thus prevent threading or unthreading of keys; when the spring loaded cover is withdrawn against the spring, the open segment is exposed for threading or unthreading of keys.